Bulunan: 240 Adet 0.001 sn
Koleksiyon [20]
Tam Metin [2]
Yayın Türü [6]
Yazar [20]
Konu Başlıkları [20]
Yayıncı [20]
Yayın Dili [2]
Dergi Adı [20]
Hyperbranched homo and thermoresponsive graft copolymers by using ATRP-macromonomer initiators

Allı, Sema | Allı, Abdulkadir | Hazer, Baki

Article | 2012 | Journal of Applied Polymer Science124 ( 1 ) , pp.536 - 548

Macromonomer initiators behave as macro cross-linkers, macro initiators, and macromonomers to obtain branched and cross-linked block/graft copolymers. A series of new macromonomer initiators for atom transfer radical polymerization (MIM-ATRP) based on polyethylene glycol (M n = 495D, 2203D, and 4203D) (PEG) were synthesized by the reaction of the hydroxyl end of mono-methacryloyl polyethylene glycol with 2-bromo propanoyl chloride, leading to methacryloyl polyethylene glycol 2-bromo propanoyl ester. Poly (ethylene glycol) functionalized with methacrylate at one end was reacted with 2-bromopropionyl chloride to form a macromonomeric . . .initiator for ATRP. ATRP was found to be a more controllable polymerization method than conventional free radical polymerization in view of fewer cross-linked polymers and highly branched polymers produced from macromonomer initiators as well. In another scenario, ATRP of N-isopropylacrylamide (NIPAM) was initiated by MIM-ATRP to obtain PEG-b-PNIPAM branched block/graft copolymers. Thermal analysis, FTIR, 1H NMR, TEM, and SEM techniques were used in the characterization of the products. They had a thermo-responsive character and exhibited volume phase transition at â 36°C. A plasticizer effect of PEG in graft copolymers was also observed, indicating a lower glass transition temperature than that of pure PNIPAM. Homo and copolymerization kinetics were also evaluated. © 2011 Wiley Periodicals, Inc Daha fazlası Daha az

Synthesis of Polylactide-b-Poly (Dimethyl Siloxane) Block Copolymers and Their Blends with Pure Polylactide

Hazer, Baki | Baysal, Bahattin M. | Köseoğlu, Ayşe G. | Beşirli, Necati | Taşkın, Elif

Article | 2012 | Journal of Polymers and the Environment20 ( 2 ) , pp.477 - 484

The synthesis of polylactide (PLA)-b-poly (dimethyl siloxane) (PDMS) linear block copolymers and their use in blends with pure-PLA are described. PLA-b-PDMS linear block copolymers were obtained by the transesterification reaction in chloroform solution between poly(dimethyl siloxane) bis (2-aminopropyl ether) (molecular weight 2,000 Da) with PLA in the presence of stannous octoate. Molecular weights (Mw) of the block copolymers were varied from 53,800 to 63,600 Da while that of pristine PLA was 73,600 Da. The copolymers obtained were purified by fractional precipitation and then characterized by 1 H NMR, FTIR, GPC, viscometry and D . . .SC techniques. Blends of pure PLA with PLA-b-PDMS block copolymers displayed improved elastic properties (elongation up to 140%) compared to pure PLA (elongation ~9%). Thermal, mechanical and morphological characterization of the blends were also conducted. © 2011 Springer Science+Business Media, LLC Daha fazlası Daha az

Tailoring polymer architectures with macromonomer azoinitiators

Yıldız, Ufuk | Hazer, Baki | Tauer, Klaus

Review | 2012 | Polymer Chemistry3 ( 5 ) , pp.1107 - 1118

Synthesis of some novel blends of polylactide with polylactide-b-poly (ethylene glycol) block copolymers

Taşkın, Elif | Hazer, Baki | Beşirli, Necati | Çavuş, Gökhan

Article | 2012 | Journal of Macromolecular Science, Part A: Pure and Applied Chemistry49 ( 2 ) , pp.164 - 170

The synthesis of polylactide (PLA)-b-polyethylene glycol (PEG) linear block copolymers and their use in blends with pure-PLA is described. PLA-b-PEG linear block copolymers were obtained by the reaction between poly(ethylene glycol) bis (2-aminopropyl ether) (molecular weight 2000 Dalton) with PLA in the presence of stannous octoate via trans esterification. Molecular weight measurements of the block copolymers indicated that AB and ABA type block copolymers were obtained by controlling the feed ratio in the trans esterification reactions. The copolymers obtained were purified by the fractional precipitation and then characterized b . . .y 1H-NMR, FTIR, GPC and DSC techniques. Blends of pure PLA with PLA-b-PEG displayed improved mechanical properties compared to pure PLA. Thermal, mechanical and morphological characterization of the blends were also conducted. © 2012 Taylor and Francis Group, LLC Daha fazlası Daha az

The effect of erythropoietin on anastomotic healing of irradiated rats

Turkcu U.O. | Cakmak G.K. | Demir E.O. | Bakkal, Bekir Hakan | Oner M.O. | Okyay R.D. | Bassorgun I.C.

Article | 2012 | Journal of Investigative Surgery25 ( 2 ) , pp.127 - 135

Aim: The aim of the present study is to evaluate the possible protective effects of erythropoietin (EPO) on anastomotic wound healing after preoperative radiotherapy according to its pleiotropic mechanism of action. Methods: Thirty-two male Wistar albino rats were randomized into four groups containing eight rats each: ANAS group, standard resection plus anastomosis; RT+ANAS group, radiation plus standard resection plus anastomosis; ANAS+EPO group, standard resection plus anastomosis plus EPO; RT+ANAS+EPO, radiation plus standard resection plus anastomosis plus EPO. All animals were sacrificed by cardiac puncture, and anastomotic he . . .aling was measured by bursting pressure, hydroxyproline (OHP) levels, myeloperoxidase (MPO) activity and histopathological evaluations. Malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-?), and matrix metalloproteinase-9 (MMP-9) were also measured in serum specimens. Results: OHP levels in the RT+ANAS + EPO group were significantly increased compared with other groups (p Daha fazlası Daha az

Tramadol as an adjunct for levobupivacaine in axillary plexus blockade: A prospective, randomized, double-blind study

Yurtlu, Bülent Serhan | Hancı, Volkan | Ege, Ahmet | Bostankolu, Selime Evrim | Ayoğlu, Hilal | Özkoçak Turan, Işıl

Article | 2012 | Turkish Journal of Medical Sciences42 ( 1 ) , pp.55 - 62

Aim: To evaluate the effect of tramadol addition to levobupivacaine in axillary plexus blockade in a prospective, randomized double-blind study. Materials and methods: A total of 60 patients scheduled to undergo hand and forearm surgery under axillary plexus blockade were randomly divided into 2 groups. Group L received 36 mL of racemic 0.5% levobupivacaine with 2 mL of saline, whereas Group LT received 2 mL (100 mg) of tramadol instead of saline. After routine monitorization, axillary block was performed with a multistimulation technique using a nerve stimulator. Motor (finger, wrist, and elbow movements) and sensory (pinprick sens . . .ation for the cutaneous supply) block characteristics for radial, median, ulnar, and musculocutaneous nerves were determined every 5 min. Postoperative motor and sensory block duration, analgesic consumption, and numeric rating scale (NRS) scores were also recorded. Results: In each group, 2 patients had block failures. The data for the remaining 56 patients were analyzed. There were no significant differences between the study groups according to motor and sensory block characteristics of 4 nerves, block durations, analgesic consumption, and NRS scores. Conclusion: The addition of 100 mg of tramadol to 0.5% levobupivacaine for axillary brachial plexus blockade neither improved the intraoperative block quality nor prolonged the duration of postoperative analgesia. © TÜBITAK Daha fazlası Daha az

Prediction of the bottom ash formed in a coal-fired power plant using artificial neural networks

Bekat, Tuğçe | Erdoğan, Muharrem | İnal, Fikret | Genç, Ayten

Article | 2012 | Energy45 ( 1 ) , pp.882 - 887

The amount of bottom ash formed in a pulverized coal-fired power plant was predicted by artificial neural network modeling using one-year operating data of the plant and the properties of the coals processed. The model output was defined as the ratio of amount of bottom ash produced to amount of coal burned (Bottom ash/Coal burned). The input parameters were the moisture contents, ash contents and lower heating values of the coals. The total 653 data were divided into two groups for the training (90% of the data) and the testing (10% of the data) of the network. A three-layer, feed-forward type network architecture with back-propaga . . .tion learning was used in the modeling study. The activation function was sigmoid function. The best prediction performance was obtained for a one hidden layer network with 29 neurons. The learning rate and the tolerance value were 0.2 and 0.05, respectively. R2 (coefficient of determination) values between the actual (Bottom ash/Coal burned) ratios and the model predictions were 0.988 for the training set and 0.984 for the testing set. In addition, the sensitivity analysis indicated that the ash content of coals was the most effective parameter for the prediction of the ratio of bottom ash to coal burned. © 2012 Elsevier Ltd Daha fazlası Daha az

Poly(3-hydroxyalkanoate)s: Diversification and biomedical applications: A state of the art review

Hazer, Derya Burcu | Kılıçay, Ebru | Hazer, Baki

Review | 2012 | Materials Science and Engineering C32 ( 4 ) , pp.637 - 647

Biomaterials have played an important role in the treatment of disease and the improvement of health care. Synthetic and naturally occurring biodegradable and biocompatible polymers have been used as biomaterials. Polyhydroxyalkanoates (PHAs) are promising materials for biomedical applications because they are biodegradable, non-toxic and biocompatible. We will shortly summarize the modification reactions, which include functionalization and grafting reactions, to improve the mechanical, thermal and hydrophilic properties of PHAs. The use of the modified PHAs in numerous biomedical applications, such as sutures, cardiovascular patch . . .es, wound dressings, scaffolds in tissue engineering, tissue repair/regeneration devices, drug carriers will be discussed in this review. © 2012 Elsevier B.V. All rights reserved Daha fazlası Daha az

Rosiglitazone treatment reduces hippocampal neuronal damage possibly through alleviating oxidative stress in chronic cerebral hypoperfusion

Özaçmak-Sayan, Hale | Özaçmak, Veysel Haktan | Barut, Figen | Jakubowska-Doğru, Ewa

Article | 2012 | Neurochemistry International61 ( 3 ) , pp.287 - 290

Oxygen free radicals and lipid peroxidation may play significant roles in the progress of injury induced by chronic cerebral hypoperfusion of the central nervous system. Rosiglitazone, a well known activator of PPAR?, has neuroprotective properties in various animal models of acute central nervous system damage. In the present study, we evaluate the possible impact of rosiglitazone on chronic cerebral hypoperfused-rats in regard to the levels of oxidative stress, reduced glutathione, and hippocampal neuronal damage. Chronic cerebral hypoperfusion was generated by permanent ligation of both common carotid arteries of Wistar rats for . . .one month. Animals in treatment group were given rosiglitazone orally at doses of 1.5, 3, or 6 mg/kg per day of the 1 month duration. The treatment significantly lowered the levels of both malondialdehyde and neuronal damage, while elevated the reduced glutathione level markedly. These findings suggest that the beneficial effect of rosiglitazone on hypoperfusion-induced hippocampal neuronal damage might be the result of inhibition of oxidative insult. © 2012 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Large caseous mitral annular calcification: With mitral stenosis, dynamic left ventricular outflow obstruction, and syncope

Akpinar I. | Karabag T. | Sayin M.R. | Yildirim N. | Dogan S.M. | Aydin M.

Article | 2012 | Texas Heart Institute Journal39 ( 6 ) , pp.910 - 912

[No abstract available]

Epicardial mass causing cardiac compression: An unusual involvement in lymphomatoid granulomatosis

Karabag T. | Aydin M. | Barut F. | Buyukates M. | Dogan S.M. | Celik O. | Sayin M.R.

Article | 2012 | Texas Heart Institute Journal39 ( 1 ) , pp.116 - 118

Lymphomatoid granulomatosis is a rare, diffuse, large B-cell lymphoma that is positive for Epstein-Barr virus. A multiorgan process, it manifests itself chiefly in the lungs but can also affect the skin, nervous system, and kidneys. Cardiac involvement and pericardial effusion are very unusual. We report the case of a 62-year-old man with lymphomatoid granulomatosis involving the heart and lungs. Diagnosis was confirmed with wedge biopsy at pericardiotomy, and the patient was treated with cyclophosphamide, prednisolone, and vincristine. Although the patient was still symptomatic at 6-month follow-up, he was in partial remission with . . . improved functional capacity. © 2012 by the Texas Heart ® Institute, Houston Daha fazlası Daha az

Eicosanoids mediate cellular immune response and phenoloxidase reaction to viral infection in adult Pimpla turionellae

Büyükgüzel, Ender

Article | 2012 | Archives of Insect Biochemistry and Physiology81 ( 1 ) , pp.20 - 33

Nodulation is the predominant insect cellular immune response to microbial infections. We posed the hypothesis that parasitoid insects in their adulthood express melanotic nodulation reactions to viral challenge and that eicosanoids mediate nodulation reactions and phenoloxidase (PO) activation in response to viral challenge. To test this idea, we injected Pimpla turionellae adults with indomethacin, a nonsteroidal anti-inflammatory drug, immediately prior to intrahemocoelic injection of Bovine herpes simplex virus-1 (BHSV-1). Treating newly emerged adults of P. turionellae with BHSV-1 induced nodulation reactions, and decreased PO . . .activity at high viral doses. Relative to vehicle-treated controls, indomethacin-treated adults produced significantly reduced numbers of nodules following viral infection (down from approximately 21 nodules per adult to less than six nodules per adult). In addition to injection treatments, increasing dietary indomethacin dosages (from 0.01% to 0.1%) were associated with decreasing nodulation (by six-fold) and PO (by about three-fold) reactions to BHSV-1 injection. Wasp adults orally fed with the lowest dietary indomethacin concentration (0.001%) expressed significantly increased PO activity (1.45 unit/min/mg protein) while nodulation reaction was not affected in response to viral challenge compared to control adults. We infer from these findings that cyclooxygenase (COX) products, at least prostaglandins, mediate nodulation response and PO action to viral infection in adults of these highly specialized insects. © 2012 Wiley Periodicals, Inc Daha fazlası Daha az

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